Ventricular Tachycardia (VT) is a major public health problem occurring in 15% of patients with coronary artery disease, 8% of patients with hypertension, and 2% of the general population. Current therapy is placement of an implantable cardioverter- defibrillator (ICD). While ICDs are effective in terminating VT, they do not prevent VT from occurring. Permanent cessation of VT can result from identification and selective ablation of the origination site(s) of the arrhythmia. This technique unfortunately can only be applied to small number of VT patients because it requires their having slow, hemodynamically stable VT to be safe. Using three proven technologies, we will create a novel means of minimally invasively identifying and ablating VT initiation sites that is applicable to a much largr number of VT patients. By combining a non-invasive mapping technology with a precise epicardial navigation approach and a flexible needle- based radio frequency ablation technique, we will produce a uniquely capable system. In Phase I of this work, we will demonstrate that these technologies can be unified while in Phase II we will verify its efficacy in an animal model. PUBLIC HEALTH RELEVANCE: Ventricular Tachycardia (VT) is a major public health issue in the United States resulting in 300,000 deaths each year. An implantable cardioverter-defibrillator is considered the most appropriate means of treatment at present. Unfortunately, this does not prevent VT but rather stops the arrhythmia with a painful shock. To permanently treat VT, its origination must be prevented, but this can presently be done on only a small percentage of the VT-affected population. The therapy that will be developed through this proposal will significantly expand the number of VT patients who can have this permanent cessation technique and will do so using a safe, cost-effective approach that builds upon several well-understood technologies. !